Naturally occurring early onset insulin dependent diabetic Golden Retriever dogs are being used in a series of experiments to investigate various parameters in diabetes mellitus. Included in the investigation are studies involving pathology, immunology, platelets, leucocyte function, basement membranes, anti-islet antibody, transplants and the hormonal milieu. The dogs have high blood sugar, low insulin concentrations ketones and sugar in the urine and are insulin-requiring. Body weight, cortisol, T2, T4, growth hormone, amylase and lipase are within normal limits. The diabetic dogs are "brittle" and hypoglycemic episodes are common. Histopathology reveals an absence of islets although grossly the pancreas appears normal.